newb gas question

[2kids]

Is it okay to just run unleaded in these slants or am I suppose to be doing a fuel additive of some kind?

Thanks!
Darcy

 

[CudaChick1968]

Generally speaking, for good performance the higher the octane, the better. You can run 87 -- the 'cheap stuff' -- if you've had hardened valve stem seals installed.

 

[805moparkid]

i believe it was 72 or 73 when Chrysler change the slant cyl head from "soft" seats to hardened exhaust seats. its pretty cheap to have the hardened exhaust seat installed and .080 off the head.

if u don't have the money to do that at the moment then the best thing is to richen up the mixture and that will help to cool the exhaust down. get it running good and just back out the mixture screw about 1/2 to 1/4 turn more.

 

[66RedFish]

This is a question I've wondered about too, so I'd be interested in seeing what others have to say on the subject. My '66 225 w/89K miles seems to run smoother and quieter on 89 octane vs. 87 octane (especially up hills), although I wouldn't call what I hear when it's running on regular as "knocking". I do also throw in a bottle of lead substitute every other tank or so, but opinions seem to vary on whether this is needed, harmful, or has no effect. I haven't yet given the car a complete tune-up (still need to replace points & condenser, check timing & valves), so maybe what I'm observing will go away once it's fully tuned. Of course even if it starts running better on regular, using unleaded could still be causing some damage to the valves.

Steve

 

[805moparkid]

This is a question I've wondered about too, so I'd be interested in seeing what others have to say on the subject. My '66 225 w/89K miles seems to run smoother and quieter on 89 octane vs. 87 octane (especially up hills), although I wouldn't call what I hear when it's running on regular as "knocking". I do also throw in a bottle of lead substitute every other tank or so, but opinions seem to vary on whether this is needed, harmful, or has no effect. I haven't yet given the car a complete tune-up (still need to replace points & condenser, check timing & valves), so maybe what I'm observing will go away once it's fully tuned. Of course even if it starts running better on regular, using unleaded could still be causing some damage to the valves.

Steve

well for a low comp engine u will actually loss hp with premium gas rather that with reg because the higher octane fights detonation, or combustion, making it harder to fire the cylinder.